Method of making electric fuses.



THOMAS E. MURRAY. or vnizw rolex,l N. Y.

METHOD OF MAKING ELECTRIC FUSES.

gaseosa.

p Application filed November 20. 1917.

buaZZ iff/om t may concern "Be it known that I, THOMAS a citizen of theUnited States. residing at New York. in the county of New York and Stateof New York, have .new and useful Improvement in Methods of E. MURRAY,

Making Electric Fuses, of which the following is a specification. A

he invention is a method of making an electric fuse of the type moreparticularly hereinafter describec.

u the accompanying` drawings` Figures l, 2 and 3 illustrate respectivelythe different steps of my process, showing the molding apparatus invertical section.

ig. 4 is an elevation of the fuse case. Fig. 5 is an end view thereof,and F ig. 6 shows a modification of the means for attaching the middleportion of. the fuse case to the plaster of'Paris ends thereof.

Similar numbers of reference indicate like parts'.

The fuse case and fuse. which are made by my process comprise a hollowtubular body portion l, having at flanges 2. The extremities of the bodyportion l are closed by plaster of Paris plugs 3, 4, in which the ianges2 are embedded.

etal rods 5, 6, whichform nals, are embedded in the end plugs 3, 4.

etween said terminals extends the fuse strip 7, passing through theplugs 3, 4 and through a mass 8 of comminuted refractory material, suchas dry plaster, which fills the space within the tubular body portionl-Vand i If desired, the tububetween the plugs 3, 4. larvbody portion lmay paper lining 9.

Instead ofmaking flanges 2 at the ends of the tubular body. portion l,struck up projections l on the inner side of said body portion near theextremities thereof, which projections engage with the plaster of Parisplugs.

I carry out my method of making this fuse in the following manner:

Having preparedv la mold 11 hav1ng a socket in its upper face conformingto-the shape of the plug 4, and below said socket a recess conforming tothe shape of the terminal 6,' I rst insert into said socket the tubularbody portion'l for a distance about one-half the depth of said socket. Ialso insertthe terminal 6 in the recess belo f said socket. The fusestrip carrying the terminal at its upper end should be sufficientlyrigid be provided with a Specieaton of Letters Patent.

invented a certain lll its ends inturnedthe fuse termi- I may form ithus guarding Patented Nov. 26, 1918. serial No. 202,949.

then to stand up in vertical position.- Into the ope'n upper extremityof the4 tubular body portion l, I pour liquid plaster of varis. untilthe socket in the mold 11 is mold, as shown in I* ig. l. In the plug 4so formed are embedded the ianges on the lower end of tube l, a portionof theterminal G and a portion of the fuse strip 7. Preferably after theplaster plug 4 has become hard, I fill into the tube 1 the commil massof refractory insulatin rial-which-niay be dry pl 8, to a level aboutthe same distance from of plug 4 is from the lower flanges of said tube.The resulting condition of the .parts is then as shown in Fig. l. I thenput into the commiiiuted material 8 a quantity of plaster of aiis in aviscous or moldable state, to forni roughly a plug of about the samelength as the lmold plug 4. Th end of this plug, as shown in Fig. 2. maybe roughly shaped by hand. In this plug is embedded the flanges attheripper extremity of tube l, a portion of the fuse strip 7 and a portionof the upper terminal 5. The fuse is electrically and mechanicallycomplete in this condition, and, if desired, may be removed from themold l1, and put into use; but in order to obtain a better finish, Iprefer to apply to the roughly shaped body of now forming the plug 3 andwhile and hence before it has A 'g 3, similar in all mold 11, so thatwhen said mold is pressed downwardly, the exposed portion of the viscousplaster assumes the same shape as the exposed or end portion of the plug4, so thatl both ends of the fuse are nicely'rounded. -After all theplaster has firmly set, the molds 1l and 12 are taken away, and the fuseappears as'in Fig. 4, ready for use.

It is to be especially noted that the joints between fuse strip andterminal rods are completely embedded in the plaster end plugs, and soalso that the plugs extend beyond the extremities of the casing,

said extremities and preventing any possi le short-.circuiting of thefuse, as may happen when the casing is closed or covered at its ends bymetallic caps: so that the casing and plugs are united simply byinwardly turned projections on the casing,

e convex top or outer ed up to about the level of the top of the such asthe flanges 2 or struck up 'projections 10, and also that the casingends register in outside diameter with the shoulders on the plugs, sothat the exterior of the fuse presents a smooth finish.

I claim:

1. The method of making a fuse of the construction set forth, Wluchconsists in, first, inserting into a suitable socket 'in a mold and fora predetermined distance the tubular body portion of said fuse, and alsoinserting into a recess in the bottom of said socket a fuse terminalandl the fuse connected thereto, the said fuse carrying at its u'pperend the opposite fuse terminal; second, pouring liquid, plaster into theupper open end of said body portion until said plaster -rises to asutiicient height in said socket to embed a' portion of said tubularbody, and to cover the inner end of the.. fuse terminal therein; third,packing comminuted refractory material into said tubular portion toposite end of said partly lill the same, and fourth, introducin plasterin a viscous state into the unfilled portion of said tubular body totill said body, and to extend beyond the same so as to 'embed the end ofthe fuse strip and a, pordown upon the protruding mass of viscousplaster to mold said body of plaster into the same shape as the body ofplaster at the opfuse.

In testimony whereof I have aiiixe'd my signature in presence of twoWitnesses.

TI-IGMAS E. MURRAY.

